Aircraft employ a wide variety of doors which are exposed to the surrounding environment about the aircraft. For example, access doors and panels permit access to the interior of the aircraft adjacent mechanical and electrical sub-system components for inspection, maintenance and repair. Passenger ingress and egress doors and storage compartment doors permit access to the aircraft interior for passage of passengers and/or cargo therethrough. Such doors and panels are typically opened and closed while the aircraft is on the ground. In addition, there is a variety of flight actuated doors which are opened and closed during various times during aircraft flight. Common examples of flight actuated doors are weapons bay doors (in military aircraft), sensor suite doors, landing gear doors and auxiliary air doors.
Aircraft are subjected to various external and internal loads which may result in temporary deformations of the door frames which are located at various places about the aircraft. For example, it is typical for an aircraft to store fuel within its wings. Thus, when the aircraft is fueled the wings may tend to droop, and the bottom side of the fuselage to be in a compressive state. When the aircraft is in flight, a variety of aerodynamic forces may act to upwardly push the wings, and cause the bottom side of the fuselage to be in a relative. tension state. Where there are doors located at regions of the aircraft which are locally subject to such tension and compression forces (e.g., landing gear doors and weapons bay doors) the door frames thereof may deform. Such deformation may occur both in the plane of the door frame and out of the plane of the door frame.
These deformations may result in the formation of gaps or discontinuities between the door and the door frame. As one of ordinary skill in the art can appreciate, these gaps or discontinuities tend to increase the radar signature of the aircraft. As such, the reduction or mitigation of any gaps or discontinuities at or around the door frame is highly desirable.
In addition, it is often desirable that aircraft doors must be able to withstand pressure differentials between the interior and exterior of the door. Typically the interior pressure is greater than the external pressure (i.e., burst pressure). Such a pressure may be a function of the placement of the door upon the aircraft, altitude, and relative aircraft speed. A positive cabin pressure is typically maintained to provide for a hospitable environment. The door frame deformations, however, may result in poor or improper sealed engagement between the door and the door frame.
Though conventional aircraft doors are provided with seals about the perimeter of the door, such seals possess certain deficiencies which detract from their overall utility. In this respect, a common prior art door sealing approach employs blade seals. A blade seal generally takes the form of a metal strip which extends from the door perimeter and engages a door frame when the door is in the closed position. The blade seal overlaps the gap formed between the door and the door frame. In this respect, the blade seal facilitates surface geometry continuity. Additionally, because the blade seal is formed of metal, such a design facilitates a continuity of electromagnetic conductivity across and between the aircraft door and door frame. Blade seal designs, however, require a high degree of maintenance as the seal must be precisely aligned in order to properly seal with the associated door frame. In addition, the seal must be routinely inspected and adjusted in order to compensate for wear of the blade seal contact surface.
Another common prior art approach to sealing the door/door frame gap is to utilize a caulking material or tape. This approach is typically used in access panel applications. Upon closure of the associated door or panel, this approach involves the application of a caulking material or tape over and about the door/door frame gap. The opening of the door results in a breaking of the caulking or tape seal. Each opening and closing cycle requires the reapplication of the caulking material or tape. As such, this sealing approach is both time and labor intensive.
Other prior art door sealing approaches often require the use of pneumatic, hydraulic and/or electro-mechanical actuators. For example, such actuators may be used to inflate expandable tubes or bladders interposed between a door and a door frame to thereby establish a seal thereat. These actuation devices and supporting hardware negatively impact space and weight requirements which may be of a paramount concern. For example, the spacial constrains within an aircraft wing are typically severely limiting and the use of bulky actuator devices for use with wing access panel seals is undesirable. As such, while these door sealing approaches may be highly advantageous for some applications, such approaches may not be suitable for others.
Accordingly, there is a need in the art for a aircraft door sealing system which is capable of substantially mitigating a perimeter gap occurring between the door and the door frame and mitigating the radar signature associated with the perimeter gap.